From: Alexei Starovoitov <ast@kernel.org>
Date: Wed, 1 Dec 2021 10:10:26 -0800
Subject: bpf: Prepare relo_core.c for kernel duty.
Patch-mainline: v5.17-rc1
Git-commit: 29db4bea1d10b73749d7992c1fc9ac13499e8871
References: jsc#PED-1368
X-info: modified context in kernel/bpf/btf.c due to d9847eb8be3d "bpf: Make CONFIG_DEBUG_INFO_BTF depend upon CONFIG_BPF_SYSCALL" already applied
Make relo_core.c to be compiled for the kernel and for user space libbpf.
Note the patch is reducing BPF_CORE_SPEC_MAX_LEN from 64 to 32.
This is the maximum number of nested structs and arrays.
For example:
struct sample {
int a;
struct {
int b[10];
};
};
struct sample *s = ...;
int *y = &s->b[5];
This field access is encoded as "0:1:0:5" and spec len is 4.
The follow up patch might bump it back to 64.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-4-alexei.starovoitov@gmail.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
include/linux/btf.h | 81 ++++++++++++++++++++++++++++++++++++++++++++++
kernel/bpf/Makefile | 4 ++
kernel/bpf/btf.c | 26 ++++++++++++++
tools/lib/bpf/relo_core.c | 76 ++++++++++++++++++++++++++++++++++++-------
4 files changed, 176 insertions(+), 11 deletions(-)
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -144,6 +144,53 @@ static inline bool btf_type_is_enum(cons
return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
}
+static inline bool str_is_empty(const char *s)
+{
+ return !s || !s[0];
+}
+
+static inline u16 btf_kind(const struct btf_type *t)
+{
+ return BTF_INFO_KIND(t->info);
+}
+
+static inline bool btf_is_enum(const struct btf_type *t)
+{
+ return btf_kind(t) == BTF_KIND_ENUM;
+}
+
+static inline bool btf_is_composite(const struct btf_type *t)
+{
+ u16 kind = btf_kind(t);
+
+ return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
+}
+
+static inline bool btf_is_array(const struct btf_type *t)
+{
+ return btf_kind(t) == BTF_KIND_ARRAY;
+}
+
+static inline bool btf_is_int(const struct btf_type *t)
+{
+ return btf_kind(t) == BTF_KIND_INT;
+}
+
+static inline bool btf_is_ptr(const struct btf_type *t)
+{
+ return btf_kind(t) == BTF_KIND_PTR;
+}
+
+static inline u8 btf_int_offset(const struct btf_type *t)
+{
+ return BTF_INT_OFFSET(*(u32 *)(t + 1));
+}
+
+static inline u8 btf_int_encoding(const struct btf_type *t)
+{
+ return BTF_INT_ENCODING(*(u32 *)(t + 1));
+}
+
static inline bool btf_type_is_scalar(const struct btf_type *t)
{
return btf_type_is_int(t) || btf_type_is_enum(t);
@@ -184,6 +231,11 @@ static inline u16 btf_type_vlen(const st
return BTF_INFO_VLEN(t->info);
}
+static inline u16 btf_vlen(const struct btf_type *t)
+{
+ return btf_type_vlen(t);
+}
+
static inline u16 btf_func_linkage(const struct btf_type *t)
{
return BTF_INFO_VLEN(t->info);
@@ -208,11 +260,40 @@ static inline u32 __btf_member_bitfield_
: 0;
}
+static inline struct btf_member *btf_members(const struct btf_type *t)
+{
+ return (struct btf_member *)(t + 1);
+}
+
+static inline u32 btf_member_bit_offset(const struct btf_type *t, u32 member_idx)
+{
+ const struct btf_member *m = btf_members(t) + member_idx;
+
+ return __btf_member_bit_offset(t, m);
+}
+
+static inline u32 btf_member_bitfield_size(const struct btf_type *t, u32 member_idx)
+{
+ const struct btf_member *m = btf_members(t) + member_idx;
+
+ return __btf_member_bitfield_size(t, m);
+}
+
static inline const struct btf_member *btf_type_member(const struct btf_type *t)
{
return (const struct btf_member *)(t + 1);
}
+static inline struct btf_array *btf_array(const struct btf_type *t)
+{
+ return (struct btf_array *)(t + 1);
+}
+
+static inline struct btf_enum *btf_enum(const struct btf_type *t)
+{
+ return (struct btf_enum *)(t + 1);
+}
+
static inline const struct btf_var_secinfo *btf_type_var_secinfo(
const struct btf_type *t)
{
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -36,3 +36,7 @@ obj-$(CONFIG_BPF_SYSCALL) += bpf_struct_
obj-${CONFIG_BPF_LSM} += bpf_lsm.o
endif
obj-$(CONFIG_BPF_PRELOAD) += preload/
+
+obj-$(CONFIG_BPF_SYSCALL) += relo_core.o
+$(obj)/relo_core.o: $(srctree)/tools/lib/bpf/relo_core.c FORCE
+ $(call if_changed_rule,cc_o_c)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6406,3 +6406,29 @@ DEFINE_KFUNC_BTF_ID_LIST(bpf_tcp_ca_kfun
DEFINE_KFUNC_BTF_ID_LIST(prog_test_kfunc_list);
#endif
+
+int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
+ const struct btf *targ_btf, __u32 targ_id)
+{
+ return -EOPNOTSUPP;
+}
+
+static bool bpf_core_is_flavor_sep(const char *s)
+{
+ /* check X___Y name pattern, where X and Y are not underscores */
+ return s[0] != '_' && /* X */
+ s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */
+ s[4] != '_'; /* Y */
+}
+
+size_t bpf_core_essential_name_len(const char *name)
+{
+ size_t n = strlen(name);
+ int i;
+
+ for (i = n - 5; i >= 0; i--) {
+ if (bpf_core_is_flavor_sep(name + i))
+ return i + 1;
+ }
+ return n;
+}
--- a/tools/lib/bpf/relo_core.c
+++ b/tools/lib/bpf/relo_core.c
@@ -1,6 +1,60 @@
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2019 Facebook */
+#ifdef __KERNEL__
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/string.h>
+#include <linux/bpf_verifier.h>
+#include "relo_core.h"
+
+static const char *btf_kind_str(const struct btf_type *t)
+{
+ return btf_type_str(t);
+}
+
+static bool is_ldimm64_insn(struct bpf_insn *insn)
+{
+ return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
+}
+
+static const struct btf_type *
+skip_mods_and_typedefs(const struct btf *btf, u32 id, u32 *res_id)
+{
+ return btf_type_skip_modifiers(btf, id, res_id);
+}
+
+static const char *btf__name_by_offset(const struct btf *btf, u32 offset)
+{
+ return btf_name_by_offset(btf, offset);
+}
+
+static s64 btf__resolve_size(const struct btf *btf, u32 type_id)
+{
+ const struct btf_type *t;
+ int size;
+
+ t = btf_type_by_id(btf, type_id);
+ t = btf_resolve_size(btf, t, &size);
+ if (IS_ERR(t))
+ return PTR_ERR(t);
+ return size;
+}
+
+enum libbpf_print_level {
+ LIBBPF_WARN,
+ LIBBPF_INFO,
+ LIBBPF_DEBUG,
+};
+
+#undef pr_warn
+#undef pr_info
+#undef pr_debug
+#define pr_warn(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
+#define pr_info(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
+#define pr_debug(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
+#define libbpf_print(level, fmt, ...) bpf_log((void *)prog_name, fmt, ##__VA_ARGS__)
+#else
#include <stdio.h>
#include <string.h>
#include <errno.h>
@@ -12,8 +66,9 @@
#include "btf.h"
#include "str_error.h"
#include "libbpf_internal.h"
+#endif
-#define BPF_CORE_SPEC_MAX_LEN 64
+#define BPF_CORE_SPEC_MAX_LEN 32
/* represents BPF CO-RE field or array element accessor */
struct bpf_core_accessor {
@@ -150,7 +205,7 @@ static bool core_relo_is_enumval_based(e
* Enum value-based relocations (ENUMVAL_EXISTS/ENUMVAL_VALUE) use access
* string to specify enumerator's value index that need to be relocated.
*/
-static int bpf_core_parse_spec(const struct btf *btf,
+static int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
__u32 type_id,
const char *spec_str,
enum bpf_core_relo_kind relo_kind,
@@ -272,8 +327,8 @@ static int bpf_core_parse_spec(const str
return sz;
spec->bit_offset += access_idx * sz * 8;
} else {
- pr_warn("relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %s\n",
- type_id, spec_str, i, id, btf_kind_str(t));
+ pr_warn("prog '%s': relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %s\n",
+ prog_name, type_id, spec_str, i, id, btf_kind_str(t));
return -EINVAL;
}
}
@@ -346,8 +401,6 @@ recur:
targ_id = btf_array(targ_type)->type;
goto recur;
default:
- pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
- btf_kind(local_type), local_id, targ_id);
return 0;
}
}
@@ -1045,7 +1098,7 @@ poison:
* [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
* where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
*/
-static void bpf_core_dump_spec(int level, const struct bpf_core_spec *spec)
+static void bpf_core_dump_spec(const char *prog_name, int level, const struct bpf_core_spec *spec)
{
const struct btf_type *t;
const struct btf_enum *e;
@@ -1167,7 +1220,8 @@ int bpf_core_apply_relo_insn(const char
if (str_is_empty(spec_str))
return -EINVAL;
- err = bpf_core_parse_spec(local_btf, local_id, spec_str, relo->kind, &local_spec);
+ err = bpf_core_parse_spec(prog_name, local_btf, local_id, spec_str,
+ relo->kind, &local_spec);
if (err) {
pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n",
prog_name, relo_idx, local_id, btf_kind_str(local_type),
@@ -1178,7 +1232,7 @@ int bpf_core_apply_relo_insn(const char
pr_debug("prog '%s': relo #%d: kind <%s> (%d), spec is ", prog_name,
relo_idx, core_relo_kind_str(relo->kind), relo->kind);
- bpf_core_dump_spec(LIBBPF_DEBUG, &local_spec);
+ bpf_core_dump_spec(prog_name, LIBBPF_DEBUG, &local_spec);
libbpf_print(LIBBPF_DEBUG, "\n");
/* TYPE_ID_LOCAL relo is special and doesn't need candidate search */
@@ -1204,14 +1258,14 @@ int bpf_core_apply_relo_insn(const char
if (err < 0) {
pr_warn("prog '%s': relo #%d: error matching candidate #%d ",
prog_name, relo_idx, i);
- bpf_core_dump_spec(LIBBPF_WARN, &cand_spec);
+ bpf_core_dump_spec(prog_name, LIBBPF_WARN, &cand_spec);
libbpf_print(LIBBPF_WARN, ": %d\n", err);
return err;
}
pr_debug("prog '%s': relo #%d: %s candidate #%d ", prog_name,
relo_idx, err == 0 ? "non-matching" : "matching", i);
- bpf_core_dump_spec(LIBBPF_DEBUG, &cand_spec);
+ bpf_core_dump_spec(prog_name, LIBBPF_DEBUG, &cand_spec);
libbpf_print(LIBBPF_DEBUG, "\n");
if (err == 0)